Hominid vs. hominin

Once genetics entered the picture, the definitions of hominids and hominins changed. Credit: K. Cantner, AGI.

Before genetics came along and revealed just how closely modern humans and chimpanzees are related, humans were classified in their own family, Hominidae, separate from old world monkeys, which were in the family Pongidae.

But once humans and chimps were shown to share approximately 99.4 percent of their genomes, some researchers proposed combining the families and reclassifying chimps from Pan troglodytes to Homo troglodytes. This ignited a firestorm of controversy, and the compromise was to leave chimps in the genus Pan but to lump the great apes and humans into the family Hominidae, which now includes orangutans, gorillas, chimps, bonobos and humans, collectively known as hominids. The term “hominin” now refers to all species of modern humans and early humans after their split from chimps about 14 million years ago.

The change is a prime example of how adopting new names in the field of paleoanthropology can be difficult, says Fred Spoor, a paleoanthropologist at the University College London in England. “When we start fiddling with names, everybody gets confused,” he says. “The transition over the last decade from hominids to hominins when we talk about human ancestors has been a pain. We’ve had to explain and re-explain, and people still get it wrong half the time.”